The present invention generally relates to the field of power converters, and more particularly to a power converter adapted to provide a selectively programmable DC voltage output based on either an AC or DC voltage input.
As the use of mobile electronic products, such as PC notebooks, PDAs, Cellular Telephones and the like, continues to increase, the need for low costs, compact power supplies to power and recharge these products, also, continues to increase. Today, in order to meet their customer""s mobile power supply needs, most manufacturers include mobile power adapters along with their mobile products.
Today""s power adapters are typically AC-to-DC, or DC-to-DC power converters which are configured to either step-up or step-down the DC voltage input delivered to the mobile device. With AC-to-DC adapters, for example, users can power most mobile devices by simply plugging the adapter into a simple AC wall outlet found in most homes or offices. Similarly, when only DC input power is available, such as in an automobile or airplane, users can still power their mobile devices by simply using a DC-to-DC converter adapter. Often, these adapters are specifically designed and tailored to provide a regulated DC output voltage, which range from between 5VDC to 30VDC depending on the kind of mobile device being powered.
Although these power adapters conveniently provide direct power and recharging capabilities, users are often required to carry separate adapters to provide power to each individual mobile device. This often means that users have to carry multiple adapters: one for an AC input power source, and another for a DC input power source. Thus, by carrying more than one device at a time, mobile device users are often forced to carry extra bulk in the form of two distinct power supplies to power two distinct mobile devices.
Accordingly, there exists a need for a power conversion device that resolves the system management problems associated with carrying all of the different power supply components necessary to power a wide variety of mobile or portable devices. Moreover, such a device would advantageously encompass serving the power supply needs of all these different mobile devices, while supplying a steady, regulated DC power output in response to either a changing AC or DC input voltage.
The present invention achieves technical advantages as a power converter capable of supplying a DC output from either an AC or DC input covering a wide range of voltage and current combinations, through external programmability, and suitable for a variety of mobile or stationary product offerings. Such a invention resolves the system management problems associated with carrying all of the different interface components necessary to power a wide variety of mobile or portable products.
In one embodiment, the invention is generally a power converter capable of receiving either an AC input voltage or DC input voltage and generating a programmable DC output voltage. The converter comprises a first circuit that converts an AC input voltage to a predetermined DC first output voltage, and a second circuit that converts a DC input voltage to a predetermined second DC output voltage. The converter also comprise a third circuit which is adapted to receive the first and second DC voltages from first and second circuits so as to generate a selectable output DC voltage.
In selected embodiments, the first and second DC output voltages provided by the first and second circuits, respectively, are generally the same value and are coupled to a common node that feeds the input terminal of the third circuit. Moreover, the third circuit is adapted to provide a selectable output DC voltage which may be set higher or lower than its DC input voltage. The third circuit may also be adapted to couple a set of removable programming keys that provide for a different associated DC output voltage. The programming key comprises a resistor, which may provide for a variety of functions, such as current-limiting, over-voltage protection, output voltage programming, and wrong-tip circuit protection.
Accordingly, the invention advantageously provides an inventive embodiment that allows mobile product users to supply power or recharging capabilities to a variety of mobile products with a single, low cost, compact device.